Sir Robert is a 40-year-old undersecretary of foreign affairs in the House of Commons. He is widely respected as a man of principle and seems to embody moral perfection to his wife and his social circle. Despite his stern public face and reputation for absolute honesty, he harbors a hidden past regarding how he built his early fortune. He finds himself torn between his political ambition and his wife's stringent expectations.

Lady Gertrude is the 27-year-old wife of Sir Robert. She is a champion of women's rights and education who combines her modern political views with an unyielding fixation on moral purity. She holds her husband to an impossible standard of perfection. She believes she can only love a man she can worship, making her entirely unaware of the ethical compromises common in political life.

Mrs. Cheveley is a 27-year-old woman who lives in Vienna and dabbles in international politics. Duplicitous and self-serving, she possesses an amused smile that suggests she is always scheming. She seeks to use a secret from the past to extort her peers for political and financial gain. She openly rejects the rigid moral constraints of Victorian society in favor of personal power.

Viscount Arthur Goring is the 34-year-old son of Lord Caversham and a close friend to the Chilterns. Known as a dandy who embraces a life of aesthetic pleasure and witty banter, he is frequently dismissed by older society as frivolous. Underneath his stylish exterior, he is highly perceptive and deeply compassionate. He consistently sees through the hypocrisies of Victorian moralism and acts as an insightful advisor to his friends.

Mabel is Sir Robert's younger sister. She is playful and flirtatious. She openly dismisses serious Victorian social duties and conventions. She possesses a natural understanding of love and society, making her highly compatible with Viscount Arthur Goring's modern sensibilities.

Lord Caversham is a 70-year-old Whig politician and father to Viscount Arthur Goring. He represents traditional Victorian society and views modern, aesthetic lifestyles as amoral. He constantly pressures his son to abandon his bachelorhood in favor of a respectable marriage and a conventional political career.

Lady Markby is a pleasant and popular older woman who embodies traditional notions of femininity and propriety. She adheres closely to social graces and frequently complains about the impact of modern politics on domestic married life.

Baron Arnheim is a deceased, wealthy figure from Sir Robert's past who lived by a philosophy of pursuing power and luxury above all else. He tempted a young Sir Robert with wealth in exchange for political secrets. His influence serves as the catalyst for the central conflict.

Lady Basildon is an invited guest at the Chilterns' party, described as very pretty and fragile. She engages in cynical banter about her perfect husband and the boredom of social expectations. She shares complaints about rigid gender roles while attending social events.

Mrs. Marchmont is a guest at the Chiltern home who matches Lady Basildon's cynical banter. She complains about her husband's perfection and openly mocks the moralizing social movements championed by hosts like Lady Gertrude Chiltern.

Tommy is Sir Robert Chiltern's secretary. He is highly conventional and predictable. He proposes to Mabel Chiltern on a regular, seasonal schedule, much to her exasperation.

Phipps is Viscount Arthur Goring's stoic and efficient butler. He serves as a sounding board for his employer's aesthetic philosophies and handles the complex maneuvering of unexpected house guests.

Vicomte de Nanjac is a guest at the Chilterns' party who briefly competes for Mabel's attention. He represents the superficial social swirl of the London season.